RESUMO
Recently capsaicin cough provocation test becomes a standardized method for evaluation of cough reflex in different physiologic and disease states. This study was done to evaluate effect of diabetic neuropathy on cough reflex sensitivity. The study included 52 age matched diabetics [20 without neuropathy-group 1, 18 with sensory neuropathy group, 14 with combined sensory and autonomic neuropathy group lI] and 10 age matched normal subjects as control group IV]. Capsaicin cough provocation [logc5] and methacholine bronchial provocation [PD20] were done to all subjects. We found reduced cough reflex sensitivity and airway reactivity in diabetics with neuropathy and the reduction was greater in those with combined sensory and au tonomic than in those with only sensory neuropathy [p < 0.001 for all]. In diabetics without neuropathy airway reactivity was not affected [p = 0.252] but cough reflex was significantly reduced [p <0.027]. No sex related differences were found in cough sensitivity in all studied groups [p>0.05 for all]. We have found significant positive correlation between PD20 and log C5 in neuropathic groups [r = 0.499- group II and r = 0.683 group Il] but in those without neuropathy it was non-significant r = 0.21]. Also a significant positive correlation was found between log C5 and duration of neuropathy in both neuropathic groups [r= 0.481 and r = 0.546 respectively]. We concluded that cough reflex sensitivity is reduced in all diabetics with greater affection in neuropathic patients while airway reactivity is reduced only in patients with neuropathy